What grip and technique is depicted in this image?
It’s a reverse grip, aka icepick or pakal grip, very loosely held (or the picture was taken before he completed the transition to a firm grip).
Too late to edit: as far as what technique, I don’t think we can tell from that still, we’d need to see a video. What’s that from, anyway? Looks fun.
I haven’t seen that episode yet, but it looks like Jim Caviezel from the TV show Person of Interest.
It’s not a reverse grip, or at least not a standard reverse grip. Or even one that I’ve ever seen in the real world.
That’s a kitchen knife, it’s got no guard. The standard, and effective, reverse gripplaces the thumb on top of the butt on knives like that so that the fingers don’t slip over the blade when you stab. That also allows you to punch with the knife hand if needed. On knives with prominent guards all fingers are used to provide a better hold.
That grip has the index finger placed on the butt. :eek:
That provides far less protection against the hand slipping when stabbing. It makes it impossible to punch. Most importantly, it restricts the range of motion in the wrist to the point where it becomes effectively impossible to stab or slash forwards .
You can try this yourself. Hold the knife in a reverse grip with the thumb on top of the butt. You will find that you can effectively move the knife through a range from that shown in the photo all the way to 90o from the arm. It’s that 90o angle that makes it possible to stab forwards or to draw across the body.
Now try holding the knife as in the photo: with the index finger on the butt. You will find the the best you can manage now is about 45o from the arm. The only way that you can now stab is to bring the point behind the opponent and drag the knife back towards your own body. That’s a useful technique, but you sure as hell don’t want it to be the *only *technique you can use. Similarly, the only effective way to draw the blade across the opponent is to swing the forearm almost parallel to the cutting path and follow through with the elbow. Once again, an effective technique but not one that you want to be your *only *option
So the short answer to the OP is that it’s a Hollywood grip. Something made up by a Hollywood choreographer with no experience in actual knife techniques because it looks cool. Or possibly produced because the actor didn’t learn what the instructor taught him.
It’s not a grip that could be used in the real world.
What’s the advantage of a reverse grip, anyway? it seems as though it would be inferior to a standard, blade-forward-thumb-on-top grip.
Right, that’s why I said it’s either a really loosely held reverse grip, or the still was taken as the guy was transitioning the knife to a properly held reverse grip. The only reason I can think of to actually hold a knife like that is if you have your arms down by your side and are trying to hide the knife against your forearm.
It is in some ways, as it has less reach than a forward grip, but there are some techniques where it can be very useful, like slashing across the biceps and forearms. If you’re brush blocking an opponent’s extended arm and trying to slash his bicep as you sidestep past him to the outside, trying to slash the bicep with a forward grip is awkward and hard to do with force, but a reverse grip with the edge out uses similar body mechanics to a punch, has more force behind it and feels more natural.
The reverse grip is, quite simply, the strongest hold for a stabbing attack. This could be a crucial factor in a defense situation. Try holding a dummy knife in different grips and try them out against a firm target and you’ll see the difference. The rapier hold is actually the weakest, especially with the thumb flexed straight (even if it’s braced against a ramp or a nub in the handle.)
BTW, my training with knives is a bit informal. My teachers didn’t train me how to fight with a knife; they taught me how to kill with one. It’s one of those dopes that I keep at the back of my head.
My knife technique is somewhat more theoretical than practiced, but the authorities I can bring to mind deprecate both the “hammer” and “icepick” grips as too limited in range of motion and too easy for even a slightly skilled opponent to block. I can’t tell from this picture if the blade wielder is changing grips or using some form of the forearm grip, which strikes me as being useless except in the hands of someone who’s practiced the technique extensively. I think it’s come into prominence in media the same way the sideways gangsta pistol grip did - because it looks kewl and diff-er-ent, not because it’s a realistic, practical or worthy technique.
The proper grip of a knife you intend to do harm with is across the palm, butted against the heel of the hand, and facing forward. All else is for experts with nothing but time to perfect the technique, or idiots.
ETA: One authority I have here on the shelf talks about those who make a cult out of their weapons, especially things like the balasong. His advice when you encounter one of these cultists is not to try to emulate them; he suggests shooting them or running away, not wasting time mastering such a tricky and low-use skill.
^
I don’t doubt your assertion. But personal experience and a lot of case studies got me sold on the ice pick grip.
A bit graphic. But one knife beat 4 AK-47s. BTW, he falls under your definition of an idiot. 
- YouTube
When I was growing up the prevailing wisdom was that anyone using a reverse grip was undoubtedly showing themselves to be an untrained amateur, but you hear that less and less now. I don’t think I’ve ever met an eskrimador who didn’t consider the reverse grip a perfectly acceptable variant, even if they heavily favored a forward grip themselves. At any rate, I’d say comparing the reverse grip to the Hollywood “gangsta style” gun grip goes way, way too far - a considerable number of instructors teach the reverse grip as a valid alternative grip, but I’ve never met any handgun instructor anywhere teaching a sideways “gangsta style” method of shooting.
William Fairbairn and Eric Sykes perfected the British commando knife and developed a very efficient fighting method based on thrusts and slashing. They primarily held the knife in the “rapier” position. What’s interesting is that they developed these techniques in Shanghai while serving on the Shanghai Municipal Police Force.
This fascinates me, since Asia is where the reverse grip is favored in many fighting styles. Why would two British commandos suggest confronting the local well established martial knife techniques with what, for all intents and purposes, appears to be a Medieval fighting style?
I’ve studied several styles of knife fighting, but not to the degree of mastering them, just as a side interest while being involved in Karate. I feel that both grips, forward and reverse, should be combined in any serious attempt to forge a style that can deal with the multitude of Martial Arts that have spread to students and fighters in modern times. Like mixing Western Boxing with Muay Thai, combine the best of both styles … be prepared for anything.
When I did Kenpo, it was related that Ed Parker sparred with a veteran LA knife fighter that used the reverse grip with a razor sharp linoleum knife. It was sparring but Ed found the one weakness and that was the guy’s empty hand was held too far out from his body and was the vulnerable point.
I remember one wicked move with the reverse grip. It is meant to be hidden - in the palm of your hand and the blade is lucked behind your arm or covered by a sleeve. you can do an upward arcing motion up across someones ribs and pecs/and or upper biceps, and then stab straight back down into the neck and/or clavicle area with tremendous force. One wicked move.
I admire Fairbairn and Sykes and believe theirs is the root of the most effective knife techniques for general (i.e., not taking a lifetime to master) use. An hour of F/S based training can turn a combatant into an effective wielder; I can’t think of any other schools that don’t require martial-arts level training and indoctrination to reach effectiveness.
However… asking why two commanders of the empire stuck with European thinking and techniques instead of learning from the natives is self-answering. (Yes, many were more open and respectful than the trope, Fairbairn included IIRC, but still…) 
First of all, while the icepick grip has the thumb atop the butt of the knife, a true reverse grip has the thumb on the spine of the grip or wrapped around the handle depending on the size of knife and hand. The reverse grip has an entire different set of techniques than the icepick, which is primarily a stabbing method, as any attempt to slash would lead tip outward with more of a ripping action. Reverse grip is used with slashing moves and reverse stab, e.g. a 7-slash or z-slash, and requires close-in contact range. The primary advantages of the reverse grip is that the blade is relatively concealed (can be easily hidden by folding it along the forearm) and that it is nearly impossible to disarm someone barehanded if they are using this grip, e.g. you can’t “clap” the hand and wrist, forcing them to drop the knife (which is a questionable technique anyway). The disadvantage is that it minimizes the effective range of the knife; you have no more reach than you do with your fist, and so is really only appropriate with shorter blades designed primarily for slashing.
You should never punch with a straight knife in your hand; for one, unless you have a very small-handled knife or a huge hand, you cannot form a proper fist. Also, you are likely to jar or injure you hand and lose grip in the knife. There are specific types of daggers made for punching in which the blade is perpendicular to the handle and the blade protrudes out on a tang that goes between the fingers. You can strike with the pommel (if your knife has one) but really, that makes about as much sense as pistol-whipping someone. It should go without saying that you should also not change grips in mid-fight.
There is no “right” way to effect a grip; each hand and knife is different in the way that it is most comfortably and securely held. That being said, the grip shown on the image shows a grip that does not look very secure. Emulating it with a similar size chef’s knife indicates that only the last two fingers have any grip at the bottom, and the finger at the top is not very secure. The actor may have larger hands than mine, but I would have to agree that it is not a grip you would see an expert using.
With regard to the Sykes-Fairbairn method, it is designed specifically for thrusting attacks. There is no question that penetrating thrusts are far more effective than slash attacks at disabling an attacker, but they are only suitable with knives greater than 6" in blade length, and wide-bladed knives may get caught in skeletal structure. These may be impractical to carry in daily use, but then, the standard advice if you expect to get into a confrontation with someone carrying a knife is to bring a gun.
Stranger
Incidentally, Fairbairn did have some reverse grip techniques. In his book Get Tough, Fairbairn describes a reverse grip downward thrust between the clavicle and scapula intended to sever the subclavian artery, complete with awesome diagram of an about to be stabbed Nazi in the last moments of his life. If I ever were win the lottery I’d love to get an authentic Fairbairn Sykes commando knife, but they vary greatly in quality, cost in the thousands, and can be really difficult to tell from frauds and replicas, even to an expert.
NM - double post
I have a B2 that’s been authenticated; I prize it because the B2s were made in early wartime England and I can hear the faint rumble of bombs whenever I handle it. I’ve had it for close to 35 years now and bought it from the son of the man who brought it home.
Unfortunately, the prior owner polished it up considerably, making a bit of a canvas purse from a sow’s ear of it. (The blade is slightly asymmetrical, and the knurling of the handle is overlapped and tool-scarred, like most B2s - so polishing the bluing off really didn’t add much.) I got it fairly cheaply as a result.
That is so, so incredibly cool. 
While we’re talking lottery winning wish lists, I’d like to own a V42, too, but they’re so rare I’d settle for just seeing one.